1. Field of the Invention
The present invention generally relates to engines used in watercraft. More particularly, the present invention relates to cooling systems for engines adapted for use in watercraft.
2. Description of the Related Art
Watercraft can be powered by various engine configurations. Some watercraft are powered by outboard motors that are attached to the aft end of the watercraft and that contain internal combustion engines while other watercraft are powered by inboard engines contained within engine compartments formed within the body of the watercraft. The engine compartments are desirably configured as compactly as possible because they necessarily encroach upon the limited floor space of the watercraft.
Until recently, the majority of the inboard engines utilized in smaller sport watercraft have been specially designed for use in such watercraft. The engines are compactly constructed and specially designed for use in small enclosed spaces. For instance, the engines can include specially designed cooling systems that draw coolant from the water in which the watercraft is operating.
Utilizing automotive engines in such watercraft would offer economic advantages because of lower production costs due to higher production quantities. A typical automotive engine, however, is often not properly proportioned or configured to fit within a confined engine compartment of such watercraft. For instance, the watercraft engine compartment can not accommodate the stock exhaust manifold of the automotive engine. Additionally, due to the unique cooling and exhaust systems required for use in marine environments, the stock watercraft manifold can not complement an automotive engine selected for other performance or size characteristics. Accordingly, a variety of manifold designs would become necessary.
Thus, the present invention relates to cooling systems for use with engines positioned within watercraft. The cooling systems should result in a decreased engine size and, accordingly, a decreased engine compartment size. The cooling system can use a lubricant cooler to cool the engine lubricant. Preferably, the lubricant cooler is positioned along the cooling system of the engine and exhaust system and not separately cooled. Because a separate pump is not necessary for the lubricant cooler, the number of components contained within the engine compartment can be reduced. Preferably, the engine and exhaust cooling systems are supplied with water from a pressure chamber within the jet pump unit of the watercraft, thereby rendering a further cooling water pump unnecessary.
To enable the disclosed cooling system to be more readily adapted for use with a number of engine configurations, the cooling system features a connecting member or adaptor. The connecting member serves as a transitional element between exhaust discharge ports in the cylinder block of the engine and exhaust passages in the exhaust manifold. Accordingly, exhaust passages through the connecting member desirably morph between the discharge port shapes and the manifold inlet port shapes. Thus, a single smooth transitional exhaust passage is formed between the engine and the exhaust manifold.
The illustrated connecting member also is provided with a cooling jacket that communicates with the balance of the cooling system. Because the exhaust gases passing through the connecting member are at their highest temperature at this point in the exhaust system, the connecting member and the associated exhaust passages preferably are cooled by the cooling system. Additionally, by allowing the connecting member cooling jacket to communicate with cooling jackets of the manifold, any bottlenecking connection within the cooling system is moved downstream of the connection between the connecting member and the exhaust manifold.
Accordingly, one aspect of the present invention involves a watercraft comprising an engine, an exhaust manifold, and a coupling plate joining the exhaust manifold to the engine. The engine includes at least one exhaust discharge port. The exhaust discharge port desirably has a certain shape. The exhaust manifold also has at least one exhaust inlet port which also has a certain shape, preferably different that the exhaust discharge port shape. The coupling plate preferably has at least one exhaust passage therethrough. The exhaust passage has a first end and a second end such that the first end is shaped to substantially match the exhaust discharge port shape and the second end is shaped to substantially match the exhaust inlet port shape.
Another aspect of the present invention involves a watercraft comprising an engine, a jet pump unit powered by the engine, and a cooling system having an influent portion and an effluent portion. The engine generally comprises a cylinder block, a cylinder head attached to the cylinder block, and a lubrication system communicating with a cylinder of the cylinder block. The lubrication system preferably includes an oil cooler that is in communication with the effluent portion of the cooling system. The effluent portion of the cooling system is preferably capable of draining coolant from the engine.